Some electronic cabinets store computer equipment such as circuit boards (e.g., processor boards, memory boards, networking boards, etc.), power supplies, disk drives, combinations thereof, and the like. A typical electronic cabinet has a fan assembly that moves air through an airflow pathway within the cabinet in order to remove heat generated by the equipment stored therein. Noise is a typical byproduct of the operation of the fan assembly. The amount of noise emanating from some fan assemblies, particularly from fan assemblies which include large fan motors or many fan motors, can be so substantial that the electronic cabinets storing those fan assemblies are not suitable for operating in an office environment.
Some businesses choose to locate electronic cabinets away from office areas in dedicated lab areas (e.g., separate rooms) so that the operation of the electronic cabinets does not interfere with the office areas. Often the lab areas provide a controlled environment (e.g., constant humidity and temperature, security, etc.) and provide convenient access to the cabinets (e.g., ceiling troughs and raised floors for power and network cables, space for adequate air circulation, etc.). Due to the large amount of noise typically emanating from the electronic cabinets in these areas, people who often spend a significant amount of time working in the vicinity (e.g., equipment operators, service technicians, etc.) typically wear earplugs or headphones to protect and preserve their hearing.
One electronic equipment manufacturer provides an electronic cabinet assembly having (i) a cabinet, (ii) a fan assembly located in the top of the cabinet, and (iii) a conventional noise muffling device that rests on top of the cabinet over the fan assembly in order to reduce noise emanating from the fan assembly. The noise muffling device is roughly a foot in height. The muffling device includes a grid of fiberglass padding and an outer steel housing that holds the grid over the fan assembly. A screened mesh retains the fiberglass in the grid configuration and prevents pieces of fiberglass from escaping into the air. The grid of fiberglass padding defines sets of flat sides which run parallel to the direction of the airflow pathway through the cabinet. When the fan assembly is in operation, some of the noise energy is absorbed by the grid of fiberglass thus reducing the amount of noise emanating from the cabinet.
Unfortunately, there are deficiencies to the above-described conventional muffling device. For example, in some situations, the muffling device does not adequately reduce noise emanating from the fan assembly. In particular, with the trend toward higher powered electronic components there comes the need for higher power airflow to cool those components. As such, the fan assemblies for many of the newer and larger cabinets generate such a significant amount of noise that the above-described conventional muffling device is no longer adequate to handle such situations.
Additionally, the height of the above-described conventional muffling device (e.g., roughly a foot) raises the profile of the cabinet assembly. The raised profile increases the required height of the ceiling in which the cabinet assembly resides, and may be less aesthetically pleasing than some conventional cabinet assemblies with lower profiles (e.g., conventional cabinet assemblies that do not have muffling devices).
Furthermore, the above-described conventional muffling device is rather heavy and expensive due to the steel housing that holds the fiberglass grid. The weight of the steel housing makes it difficult, particularly for shorter people, to install and remove the muffling device from the cabinet. The relative high cost of the steel housing may prohibit purchases of the muffling device even though the muffling device could substantially reduce the noise emanating from the cabinet assembly.
The above-described approach of using ear protection (e.g., earplugs or headphones) can provide effective protection to people working in the vicinity of the cabinet assembly. However, this approach cannot always be relied upon. For example, such ear protection items are cumbersome for a user to carry around, particularly if that user often enters and leaves the lab area, and are occasionally forgotten or not worn. Additionally, since such items are often construed as personal items and contact the user""s ear and/or hair, such items typically are not shared among multiple users and thus are not always available to everyone. Rather, due to resource limitations (e.g., expense, inventory control, etc.), such items are often not made freely available to all people accessing the lab area, and people that access the lab area only occasionally are often made to endure the noise instead of being protected from it.
In contrast to the above-described conventional approach to reducing noise using a muffling device having a fiberglass grid that defines a set of flat sides running parallel to the direction of the airflow pathway through the cabinet, the invention is directed to techniques for attenuating noise from a computer equipment cabinet using lateral noise absorption members which define surfaces that form sides of airflow channels therethrough. The surfaces are substantially non-parallel to a direction of an airflow pathway through the cabinet when the lateral noise absorption members are properly installed with the cabinet. The invention provides more surface area (proportionately to height) and an improved angle of incidence for absorbing sound energy than the above-described conventional fiberglass padded device having flat sides that run parallel to the direction of the airflow pathway. Accordingly, the invention can provide substantial and superior ear protection particularly to people in the vicinity of the cabinet who do not have the benefit of other ear protection (e.g., earplugs, headphones, etc.).
One arrangement of the invention is directed to an apparatus for attenuating noise from a cabinet that houses computer equipment. The apparatus includes a frame, a set of positioning members to position the frame relative to the cabinet, and lateral noise absorption members that are supported by the frame. The lateral noise absorption members define surfaces that form sides of airflow channels through the apparatus. The surfaces are substantially non-parallel to a direction of an airflow pathway through the cabinet when the set of positioning members positions the frame relative to the cabinet. The lateral noise absorption members absorb sound energy emanating from the cabinet (e.g., from a fan assembly within the cabinet). The lateral noise absorption members transform some of the sound energy into low level heat which can be dissipated into the air stream. Additionally, some of the sound energy is reflected back into the cabinet toward the source (e.g., toward the fan assembly).
In one arrangement, the lateral noise absorption members include respective foam portions to absorb noise energy exiting the cabinet in the direction of the airflow pathway when the set of positioning members positions the frame relative to the cabinet. Foam is generally lower in cost and easier to handle (e.g., easier to cut and manually manipulate) than fiberglass thus making the apparatus of the invention less expensive and easier to make than the above-described conventional muffling device that has a fiberglass grid.
Preferably, the apparatus further includes longitudinal noise absorption members that extend in a direction that is perpendicular to the lateral noise absorption members, and each longitudinal noise absorption member defines slots that hold the lateral noise absorption members in position. The longitudinal noise absorption members provide additional surface area for absorbing sound energy for additional noise reduction.
In one arrangement, the foam portion of each lateral noise absorption member defines a substantially flat surface. The longitudinal noise absorption members include respective foam portions, and the foam portion of each longitudinal noise absorption member defines a substantially dimpled surface. One skilled in the art understands that such dimpled surfaces can improve attenuation of lower frequency sound energy. As such, the foam portions of the longitudinal noise absorption members tend to have an increased capability to absorb low frequency noise energy over that of the foam portions of the lateral noise absorption members. Accordingly, this arrangement has enhanced capabilities to absorb lower frequency sound energy.
In one arrangement, each lateral noise absorption member includes a foam portion, a metallic support portion (e.g., a flexible aluminum sheet), and adhesive that fastens the foam portion to the metallic support portion of that lateral noise absorption member. The metallic support portions provide structural support for the foam portions, as well as helps reflect any sound energy, which penetrates completely through the foam portions, back toward the sound energy source (i.e., the fan assembly).
In one arrangement, each lateral noise absorption member further includes another foam portion, and additional adhesive that fastens the other foam portion to another side of the metallic support portion of that lateral noise absorption member. Accordingly, any sound energy that could otherwise reflect off of the back of a lateral noise absorption member can thus be absorbed by the other foam portion to provide further noise reduction.
In one arrangement, the frame supports the lateral noise absorption members such that an edge of each lateral noise absorption member resides over an axis of rotation of at least one fan within the cabinet when the set of positioning members positions the frame relative to the cabinet. This placement of the lateral noise absorption members is in locations that provide little disruption of the airflow provided by the fans in order to avoid substantially interfering with the air stream.
In one arrangement, the longitudinal members orient the lateral noise absorption members such that the surfaces defined by the lateral noise absorption members reside at substantially 30 degrees to the direction of the airflow pathway through the cabinet when the set of positioning members positions the frame relative to the cabinet. This 30 degree orientation results in significant sound energy absorption (e.g., due to a substantially 60 degree angle of incidence for absorbing major sound energy components along the direction of the air stream) while still allowing the air stream to flow through the apparatus in order to remove heat from the equipment within the cabinet.
The features of the invention, as described above, may be employed in data storage systems, devices and methods and other computer-related components such as those manufactured by EMC Corporation of Hopkinton, Mass.